The semiconductor technologies are developing very fast, especially for semiconductor dies which have a tendency toward miniaturization. Besides, the requirements for the functions of the semiconductor dies have an opposite tendency to variety. Namely, the semiconductor dies must have more I/O pads to a smaller area, so the density of the pins is raised quickly. It causes the packaging for the semiconductor dies to become more difficult and decrease the yield.
The main purpose of the package structure is to protect the dies from outside damages. However, the bonds of IC (integrated circuit) may be substantially impacted by the temperature variation during IC operating. In this situation, although the package is not damaged by external force, the IC still cannot perform its function properly. So it is necessary to test the bonding strength and quality of the packaged integrated circuit, in order to achieve a higher yield of the packaged IC.
With the purpose mentioned above, there is a way named “Wire Pull Testing” (WPT). Wire Pull Testing is one of several available time-zero tests for wire bond strength and quality. It consists of applying an upward force under the wire to be tested, effectively pulling the wire away from the die. There are several different failure modes of WPT, (1) first bond (ball bond) lifting; (2) neck break; (3) midspan wire break; (4) heel break; and (5) second bond (wedge bond) lifting. First or second bond lifting is unacceptable and should prompt the process operator to investigate why such a failure mode occurred. Nevertheless, with the improvement of IC package, there are many different types of package disclosed. The WPT can only apply to some traditional package like wirebonding BGA (Ball Grid Array), but cannot apply to some newer packages, such as Flip-Chip package. So the WPT method is inefficient and impractical.
To reach the purpose of testing BGA package, another way named “Ball Shear Testing (BST)” is provided. By applying a horizontal force on the bonding ball, such as solder ball, the bonding ball would be pushed in horizontal direction. There are six failure modes (by reference to JEDEC standard No. B 117) of B ST, which includes (1) Ball Shear (2) Pad Lift (3) Ball Lift: lack of solder wetting (4) Intermetallic Break (5) Shear Above Ball Centerline (6) Interference Setup Error. The first and second failure modes are acceptable, and others are unacceptable. Although this seems quite improved, it still has many disadvantages. For example, it is only suitable for Flip-Chip package but not applicable on a fan-in type and fan-out type wafer level packaging (FO-WLP) or other modified type of BGA package. The reason is that it will come out with undesired failure modes, such as the ball lifting at UBM (under bump metallurgy) which is between trace (Redistribution Layer, or RDL) and solder ball, but not the expected outcome which the broken part (QBM) is formed between bonding pad and trace.
In view of foregoing problems, it is urgently required to have a method and system for testing the bonding strength and quality of multiple-type package. The system with the aforementioned functions should be easy to upgrade and have a high reliability. The present invention therefore can match all the requirements.